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is_scalar template in C++
In this article we will be discussing the working, syntax and examples of std::is_scalar template in C++ STL.
is_scalar is a template which comes under <type_traits> header file. This template is used to check whether the given type T is a scalar type or not
This template is a combination of is_arithmetic, is_pointer, is_enum, is_member_pointer or is_same and checks whether either if either one is true, the result of is_scalar will also be true.
What is a scalar type in C++?
A scalar type is that object which is neither a class type nor an array type. A scalar type is a type which has inbuilt functionality for the addition operator without any overloading.
Syntax
template <class T> is_scalar;
Parameters
The template can have only parameter of type T, and check whether the given type is a scalar type or not.
Return value
It returns a Boolean value, true if the given type is a scalar type, and false if the given type is not a scalar type.
Example
Input: is_scalar<int>::value; Output: True Input: is_scalar<A>::value; //assuming A is an object of a class. Output: False
Example
#include <iostream>
#include <type_traits>
using namespace std;
int main() {
class TP {
};
cout << boolalpha;
cout << "checking for is_scalar: ";
cout << "\nint(TP::*): "<< is_scalar<int(TP::*)>::value;
cout << "\nint *: "<< is_scalar<int*>::value;
cout << "\nbool: "<< is_scalar<bool>::value;
cout << "\nint(int): "<< is_scalar<int(int)>::value;
return 0;
}Output
If we run the above code it will generate the following output −
checking for is_scalar: int(TP::*): true int *: true bool: true int(int): false
Example
#include <iostream>
#include <type_traits>
using namespace std;
int main() {
class TP {
};
enum class TP_1 {
var_1,
var_2,
var_3,
var4
};
cout << boolalpha;
cout << "checking for is_scalar: ";
cout << "\nTP : "<< is_scalar<int(TP)>::value;
cout << "\nTP_1: "<< is_scalar<TP_1>::value;
cout << "\nint[10] "<< is_scalar<int[10]>::value;
cout << "\nint&: "<< is_scalar<int&>::value;
cout << "\nchar&: "<< is_scalar<char&>::value;
return 0;
}Output
If we run the above code it will generate the following output −
checking for is_scalar: TP : false TP_1: true int[10] false int&: false char&: false
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